In 1973 I was working for a well known Computer Bureaux. I arrived at the data centre at 02:30 or so to be greeted by the shift leader with the usual 18 inches of hex core dump ...after and hour ish I had punched up the cards to recompile and rerun to fix the problem... IBM user manual 'probable user error' - bo*lcks. Went to machine room to load cards and saw and IBM engineer wielding a Thor like hammer with great gusto on a chain printer - whereupon he turned to me and said 'percussive adjustment' I have used a lot of percussive adjustment over the years
